GENERAL CHARACTERS OP LEPIDOPTERA. 



173 



Fio. 496. FEATHER-SCALES OK THE GOAT-MOTH. 



them is often considerable. The possession of scales upon their 



wings is not alto- 

 gether peculiar to 

 them, for they are 

 found upon the 

 wiugs and bodies 

 of other insects ; 

 but it is only in 

 those, that the \vings 

 are covered with 

 such complete layers 

 of them. The scales 



are generally of somewhat oval form, terminating at one end in 

 a kind of stalk, by which they are attached to the membrane of 

 the wing ; and on this they are arranged in rows, overlapping 

 each other like tiles on a roof. They may be easily rubbed off 

 with the finger, and the bare membrane is left, which is then 

 seen to correspond with that of the wings of other insects. The 

 number of scales covering the wings of the Silkworm Moth, has 

 been estimated at about 400,000 ; it is entirely tj these that the 

 colours of the wings are due, which are frequently so gorgeous in 

 this Order. In a few species, the wings are partially, or even 

 almost entirely destitute of scales ; but the structure of the mouth, 

 and their alliance in general characters with other species, leave 

 no doubt that they belong to this Order. Of the peculiar adapta- 

 tion of the mouth of the Insects composing this Order, for suction, 

 mention has been already made ( 674) ; and they are there- 

 fore placed at the head of the Haustellate or Suctorial group, as 

 the Coleoptera are at the head of the Mandibulate insects. Of their 

 metamorphosis, also, an account has been given ; and it now 

 only remains to describe some of the peculiarities of the larvae 

 and pupae of this Order. 



768. The first three segments of the body, in the Lepidopteroua 

 larvae, have each a pair of simple, short, and jointed feet ; which 

 are the rudiments of those of the perfect insect. Behind these are 

 a variable number of temporary appendages, called pro-legs, which 

 are thick, short, fleshy tubercles, armed at their extremity with 

 a great number of minute hooks ; and furnished with powerful 

 VOL. TI o 



